I have a vivid memory of standing by a muddy road on a dark December afternoon in 1995, when I was chatting with two friends, one a Bosnian Muslim, the other a Bosnian Serb. We were all in the Bosnian city of Tuzla, working on CNN’s coverage of a war that had already claimed 100,000 lives and displaced millions — the worst conflict in Europe since World War II. The warring parties had just signed the U.S.-brokered Dayton Accords, meant to put an end to three years of carnage.

I asked them whether they thought peace would hold, and they nearly winced at the question. But they agreed that everyone — Bosnia’s Muslims, Serbs and Croats — were tired of fighting. That alone would allow the agreement to hold.

A generation later, there are troubling signs that the hard-won peace is seriously faltering. Nationalist politicians are openly questioning the Dayton framework, which created two semi-independent “entities” within the country of Bosnia and Herzegovina: a Serb-run republic, and a federation of Croats and Muslims.

This time around, ethnic passions are rising amid a broader wave of nationalism across the continent, one ominously coinciding with a Russian campaign to undermine Western-friendly governments. If it was difficult for the West to bring an end to the fighting back then, conditions this time — with the Western alliance less united and nationalist populists making gains in many countries — would make it even more difficult to restore peace if the agreement breaks down. Europe and the United States, currently distracted with other problems, must act soon to keep Bosnia from going off the rails.

At the heart of the turmoil stands Milorad Dodik, the formerly moderate president of the Serb autonomous region that calls itself the Republika Srpska — a name chosen in 1992 by Radovan Karadzic, who was later convicted of leading a genocide against Bosnian Muslims.

Dodik has declared that he wants to secede from Bosnia and perhaps join Serbia proper. He is also backing Croats who say they want to have their own entity. The Bosnian Muslim leader Bakir Izetbegovic has responded by saying a third entity cannot be created without war.

Dodik has been defying the central government and drawing closer to Russian President Vladimir Putin, who is keen to exploit Serb grievances in the region. For the moment, Dodik has postponed a referendum on independence. But even after the top Bosnian court banned it, he held a test referendum to celebrate a national holiday on Jan. 9, the day in 1992 when Karadzic declared an independent Bosnian Serb state, which led to war. After Dodik defied the court decision, the United States imposed sanctions against him. But it has not deterred him.

This year’s Jan. 9 parade featured a very military-looking police force marching with automatic weapons, and it closed with a detachment from the Night Wolves, the Russian motorcycle gang that Putin has deployed in Crimea and Ukraine along with Russian forces. Also in the parade were the muscle-bound members of Srbska Cast, or Serbian Honor, a paramilitary group that Bosnia’s security minister says is being trained by Russians. Watching approvingly in the stands were Serbia’s ministers of interior and defense.

Bosnian leaders are growing alarmed at the stockpiling of weapons by the Serbs, who recently acquired an additional 2,500 automatic rifles, purportedly for their police force. The purchase is legal, but far out of proportion to those made by other local police units.

Dodik has been traveling frequently to Moscow, and Russian emissaries have been visiting Banja Luka, the seat of the Bosnian Serb region. During one such visit last month, Banja Luka was festooned with Russian and Bosnian Serb flags. Dodik declared, “True friends such as the Russian Federation and its President Vladimir Putin have helped us to clearly set our goals, get back self-confidence and fight for our original rights.”

Russia wants Bosnia’s Serbs to block their country from joining NATO. In addition, the Kremlin has found that growing neglect by the West makes the fragile state fertile ground for its anti-Western strategy. In effect, Russia is pushing on an open door.

With the West looking the other way, others are also drawn to Bosnia. A few days ago, Turkey’s President Recep Tayyip Erdogan held a massive rally in the capital city of Sarajevo. He was campaigning for the vote of expatriate Turks ahead of Turkish elections, but also seized the opportunity to stoke sectarian sentiment. The crowds chanted “Allahu akbar,” and “Sultan Erdogan,” as the Turkish president arrived with Izetbegovic, whose Party of Democratic Action (SDA) is developing ties with Erdogan’s Justice and Development Party, or AKP.

In October, Bosnia is scheduled to hold elections. Dodik is running for a seat in the three-member presidency. He says he is following a “path to independence.” Bosnians are worried he is leading the country to war.

To prevent a new calamity in the fractious part of the world where World War I started — and where Europe’s greatest loss of life in decades occurred — the European Union, NATO and the United States should act without delay to boost their diplomatic engagement, strengthen their presence with experienced negotiators, and revive the functions of the office of the high representative, whose job is to monitor the implementation of the Dayton agreements. The West’s thinning military presence should be beefed up at least until the elections, a plan to integrate competing police forces should be put back in motion, and the continuing affronts by Dodik and his backers should be met with a strong response.

In short, Bosnia needs urgent attention from democratic countries. Otherwise, the decades since Dayton will have amounted to a resting period between Balkan wars.